Various hydrocarbon conversion processes can utilize ionic liquid catalysts.
Alkylation is typically used to combine light olefins, for example mixtures of alkenes such as propylene and butylene, with isobutane to produce a relatively high-octane branched-chain paraffinic hydrocarbon fuel, including isoheptane and isooctane. Similarly, an alkylation reaction can be performed using an aromatic compound such as benzene in place of the isobutane. When using benzene, the product resulting from the alkylation reaction is an alkylbenzene (e.g. ethylbenzene, cumene, dodecylbenzene, etc.).
Processes for the oligomerization of light olefins (e.g. ethylene, propylene, and butylene) to produce higher carbon number olefin products (e.g. C6+ olefins) are well known. Oligomerization processes have been employed to produce high quality motor fuel components as well as petrochemicals from ethylene, propylene, and butylene. These oligomerization processes are also referred to as catalytic condensation and polymerization, with the resulting motor fuel often referred to as polymer gasoline.
The disproportionation of paraffins (e.g., isopentane (iC5)) involves reacting two moles of hydrocarbon to form one mole each of two different products, one having a carbon count greater than the starting material and the other having a carbon count less than the starting material. The total number of moles in the system remains the same throughout the process, but the products have different carbon counts from the reactants.
Isomerization of linear paraffins to their branched isomers increases their octane number and thus their value to a refiner. Isomerization processes involve reacting one mole of a hydrocarbon (e.g., normal pentane) to form one mole of an isomer of that specific hydrocarbon (e.g., isopentane). The total number of moles remains the same throughout this process, and the product has the same number of carbons as the reactant.
Acidic ionic liquids can be used as an alternative to the commonly used strong acid catalysts in hydrocarbon conversion processes. Ionic liquids are catalysts that can be used in a variety of catalytic reactions, including the alkylation of paraffins with olefins. Ionic liquids are salts comprised of cations and anions which typically melt below about 100° C.
Ionic liquids are essentially salts in a liquid state, and are described in U.S. Pat. Nos. 4,764,440, 5,104,840, and 5,824,832. The properties vary extensively for different ionic liquids, and the use of ionic liquids depends on the properties of a given ionic liquid. Depending on the organic cation of the ionic liquid and the anion, the ionic liquid can have very different properties.
Ionic liquids provide advantages over other catalysts, including being less corrosive than catalysts like HF, and being non-volatile.
Ionic liquids have also been used in separation processes, such as the removal of various contaminants from hydrocarbons as described in U.S. Pat. Nos. 7,749,377, 8,574,426, 8,574,427, 8,580,107, 8,608,943, 8,608,949, 8,608,950, 8,608,951, 8,709,236, for example, and the removal of contaminants from oxidation products as described in U.S. Pat. Nos. 8,754,254, 9,000,214, for example.
However, the use of ionic liquids presents unique and novel waste handling challenges due to the nature of the chemicals and compounds specific to the normal operation of the unit. Many of these substances, including but not limited to the ionic liquid itself, are not suitable to be released, drained, or otherwise discharged into standard refinery relief systems, waste handling systems, or other similar systems intended and designed to manage waste or unit non-product streams.
There is a need for a system for handling waste streams containing ionic liquids.